The proposed conference will be the eighth in a series of Gordon Conferences on the heart, which began in 1966 under the auspices of the Cardiac Muscle Society. In recent years it has become apparent that rhythmic firing of action potentials in cardiac tissue, as well as in smooth muscle and pacemaker neurons, is a manifestation of an underlying oscillatory property of all excitable membranes. The proposed conference will be particularly timely in bringing together workers employing diverse approaches: theoretical aspects of oscillatory activity, pacemaker ionic currents, entrainment of rhythmicity in spontaneously active cells, and tissue culture models. Investigators studying these phenomena in cardac muscle, smooth muscle and in neural systems will have the opportunity to examine each other's work and to discuss related aspects. The resulting interchange and discussion should be especially important in delineating unsolved problems and pointing the way to their eventual solution. Several of the proposed sessions will focus on recent advances which have not been discussed previously in similar meetings. For this reason a setting such as that traditional with the Gordon Conferences, which favors free and informal exchange of ideas, will be particulary advantageous. This is especially true because cardiac muscle physiologists who study pacemaker behavior of heart cells rarely have time to keep up with the publications of neurophysiologists who work with pacemaker neurons, and vice-versa. A week of high-level, informal interaction among members of these diverse groups should be productive of more than the usual number of creative insights and ideas.